Now a days we heard about phone burst or catch fire, so what is the reasons behind this, there may be many reason like, manufacture defect, battery issue, short circuit or higher radiation. So we need to check the SAR value of your phones, SAR means (Specific Absorption Rate), open your phone dialer pad type *#07#
If your phone has 1.6watt/kg than its safe for use. But If your phone has more than 1.6 watt/kg SAR value than it will harmful for you, you should change the phone or talk to the service support or manufacturer.